The present invention relates to magnetic, optical, and magneto-optic recording media disks, and in particular, it relates to bonding hubs to disk substrates.
Such recording media disks more generally consist of three elements, a substrate having one or more recording layers, a hub, and an adhesive which secures the substrate to the hub.
Typically, the substrate is made from polymethylmethacrylate, polycarbonate, polyester, aluminum or glass. The magneto-optic layer is deposited through well-known methods of sputtering on to the substrate.
A hub is then applied to the substrate. The hub generally includes a metal centering disk embedded in a polymeric flange. The typical method for attaching the hub to the substrate is to place a ring of polymer film with a pressure-sensitive adhesive coated to both sides between the substrate and the hub to secure the hub to the substrate.
In situations in which optical disks must operate in a wide temperature range, a danger exists that the hub may move relative to information stored on the active layer of the substrate. Such movement, of course, causes problems with storing and retrieving data. Furthermore, a uniform adhesive thickness or "bond line" between the hub and substrate is needed to minimize disk wobble during rotation especially on large diameter disks.